Internal combustion engine



Nov. 29, 1938.

J. L DOLL ET AL 2,138,027

INTERNAL COMBUSTION ENGINE Filed July 6, 1937 2 Sheets-Sheet 1 l9 ln a N H o 3 n A a s:

Q m '1' N N N 3 i? q S Q 23 xn 00 g Q -i S\ 3nnentors John Doll Clifford NRO ZIJ Nov. 29, 1938. .1. L. DOLL E AL 2,138,027

INTERNAL COMBUSTION ENGINE Filed July/5, 1.957 2 Sheets-Sheet 2 Em \\\\\\\\l 35 s M); 5

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Patented Nov. 29, 1938 UNITED STATES PATENT OFFICE INTERNAL COMBUSTION ENGINE Application July 6, 1937, Serial No. 152,036

8 Claims.

This invention relates to internal combustion engines and particularly two-cycle engines.

An object of the invention is to provide a very light, compact and inexpensive engine, de-

signed to operate at quite high speeds, and especially suited to serve as a power plant for model aeroplanes and other miniature vehicles.

Another object of the invention is to attach the fuel tank of an internal combustion engine to the crank case thereof, in a simple, novel, and convenient manner. I

A further object is to so assemble the crank shaft of an internal combustion engine, a head in which such shaft is journaled, and a makeand-break device for the ignition circuit, that the assembly may be conveniently attached to and detached from an engine as a unit.

A further object is to provide an improved and highly simplified make-and-break device for the ignition circuit, and to so mount and position such device as to safeguard it from dirt, grease and oil.

A further object is to arrange the cylinder of an internal combustion engine within a jacket comprising members embracing opposite halves of the cylinder, one thereof having inlet and exhaust ports and the other a by-pass for delivering a charge from the crank case to the combustion chamber.

A further object is to employ a common means for interconnecting said jacket members and attaching an exhaust fitting to one thereof.

These and various other objects are attained by the construction hereinafter described and illustrated in the accompanying drawings, whereinFig. 1 is a top plan view of the improved en- 8 c.

Fig. 2 is a side elevational view of the same, in partial section.

Fig. 3 is a front end view.

Fig. 4 is a vertical cross sectional'view, taken on the line 4-4 of Fig. 2.

Fig. 5 is a horizontal cross section taken on the line 5-5 of Fig. 4.

Fig. 6 is an enlarged, fragmentary, longitudinal, vertical, sectional view, taken on the line 6-6 of Fig. 1. Fig. 7 is a cross section .'l -1 of Fig. 6.

8 is a cross section taken on line 8--8 of Fig. 9 is a cross sectional view of the carbureting duct showing the outlet thereto of the fuel feed pipe.

taken upon the line In these views, the reference character I designates a cylinder, integrally headed at its upper end and exteriorly formed on its upper portion with numerous, heat-dissipating, spaced, annular fins 2. Set into the head of such cylinder, is a spark plug 3, having its spark gap disposed in the combustion chamber formed by the upper portion of the cylinder.

A piston 4, reciprocatory in the cylinder, has its connecting rod 5 extending into a crank-case 6 whereon the cylinder is mounted by screws 1, and within the crank-case said rod engages the crank-pin 8 of a crank disk 9 fast on a crankshaft III. The latter is journaled in a bearing I I, pressed into a circular head l2 closing one end of the crank-case and secured to the latter by screws l3. To the other end of the crank-case, is attached an approximately conical fuel tank I4, having its wall flush with that of the crankcase at their juncture, its diameter being progressively reduced toward its free end. The screws l3 extend freely through bored ribs Ma exteriorly formed on the crank-case, and are tapped into registering external ribs IS on the fuel tank, thus serving to connect both the head I2 and fuel tank to the crank case. The latter is formed with a partition [6, fully separating its crank chamber I! from a fuel space with which the tank l4 has open communication. It is preferred to extend the head I2 some distance into the crank case to suitably reduce the volume of the crank chamber for fuel compression purposes. A pair of ribs. l8, oppositely laterally projecting fro m the crank-case, serve to mount the engine on any desired support.

The head I2 is formed axially with a tubular outward extension l9, interiorly accommodating the outer portion of the bearing H and exteriorly carrying a collar 20, which mounts the ignition circuit make-and-break device. Said collar is split (preferably at its bottom), as indicated at 2|, adapting it to be clamped on the extension I9 so as to maintain a desired rotative position. Said collar is sufliciently free, however, to afford it a rotative adjustment for spark advancement or retardation, as more fully hereafter explained. Perioherally opening in said collar, diametrically opposite .to the split 2|, is a rectangular pocket 22, into which is set a fibre or other insulating support 23 having a reduced upward extension carrying a contact point 24. This support is securely clamped .in the pocket by a screw 25 and is sufliciently spaced from the bottom and a circumferential wall of the pocket to accommodate a bell rocking movement, as best appears in Fig. 6. The arm 26 projects upwardly between the support 23 and said circumferential wall and carries a contact point 28 positioned to engage the point 24. The arm 21 extends between the support 23 and the bottom of said pocket, being terminally downwardly bent to ride on a cam 29 fixed on the crank shaft. A flat spring 30 secured to the outer end of the support 23 is stressed against said circumferential wall of the pocket to urge the bell crank arm 26 toward its contact-making position and the arm 21 into engagement with the cam 29, the latter being fashioned to establish and maintain contact during the required cycle interval. The pocket walls engaged by the screw 25 are preferably adapted for such slight flexure as will permit clamping of the support 23 between such Walls. By rotatively adjusting the collar 20, the make-and-break device is angularly shifted with respect to the cam 29, to advance or retard the spark.

Embracing the lower portion of the cylinder I is a jacket comprising semi-cylindrical members 3| and 32, which preferably substantially meet in a plane axial to the cylinder, being interconnected and. clamped in place by screws 33, serving further to attach to the member 3| an exhaust fitting 34. Preferably the ends of said screws are tapped into said fitting, thus concealing such ends and eliminating necessity for nuts. The member 3| is also integrally formed with a carbureting duct 35 extending above the fuel tank in a tangential relation to the cylinder and terminally open for the admission of air. A fuel feed pipe 36 passes vertically through said duct and has a restricted outlet 31- into same, said pipe extending downwardly into the fuel tank and having a terminal inlet adjacent to the tank bottom. A needle valve 38 controlling the outlet 31 is threaded into the top portion of the pipe 36 and is elongated upwardly sufiiciently to provide for its convenient manipulation.

An opening 39 in the jacket member 3| establishes communication between the fitting 34 and an exhaust port 40 in the cylinder, and the carbureting duct communicates with an inlet port 4| of the cylinder, spaced predeterminedly beneath the exhaust port.

The jacket member 32 has its inner face recessed to form a by-pass 42, maintaining communication between upper and lower by-pass ports 43 of the cylinder, the piston being ported at 44 for registration with the lowermost by-pass port.

The disclosed engine may have a variety of uses, but is particularly suited, by reason of its light weight and compact form, for driving the propeller of a model aeroplane. Thus, there is shown a propeller 45 clamped on the forward portion of the shaft I0 between collars 46, a nut 41 being threaded on the shaft extremity for applying the clamping pressure. It is preferred, in employing such collars, to form the cam 29 integrally with one thereof, as best appears in Fig. 6, the collar 20 being recessed to accommodate the cam.

The described engine operates on the usual two-cycle principle, drawing a charge into the crank chamber II when the piston is raised, bypassing such charge to the combustion chamber when the piston is lowered and simultaneously exhausting products of a preceding combustion, and compressing the charge during, and firing it at completion of the following up-stroke.

Attaching the fuel tank, as described, to the rear end of the crank case establishes the former in a convenient and compact unitary relation to the engine and promotes a maximum simplicity in the fuel feed provision.

The engine is designed throughout to simplify its manufacture and assembly, and permit of low cost quantity production. In miniature sizes, productive of one half horse power, or less, the larger parts may be accurately and inexpensively formed as die castings, preferably from an aluminum alloy.

The invention is presented as including all such modifications and changes as come within the scope of the following claims.

What we claim is:

1. An internal combustion engine comprising a crank shaft, a crank case, a fuel tank, a crank shaft bearing, a head carrying such bearing, and

a common means for securing the fuel tank and head to the crank case.

2. An internal combustion engine comprising a crank shaft, a crank case, a fuel tank, a crank shaft bearing, a head carrying such bearing, and means for securing the fuel tank and head to opposite ends of the crank case.

3. An internal combustion engine as set forth in claim 2, said head forming a closure for the crank case.

4. An internal combustion engine comprising a crank shaft, a crank case, a fuel tank, a crank shaft bearing, a head carrying such bearing, said fuel tank and head engaging opposite ends of the crank case, and a common means for securing the fuel tank and head to the crank case.

5. An internal combustion engine comprising a crank shaft, a crank case having a partition, a crank chamber at one side of the partition and a fuel space at the other side of the partition, and a fuel tank secured to the crank case in communication with the fuel space.

6. In an internal combustion engine, a crankcase of substantially cylindrical form, and a fuel tank of approximately conical form, secured to the crank-case with its axis substantially aligned with that of the crank-case.

7. In an internal combustion engine, a crankcase of substantially cylindrical form, and members of substantially circular cross section carried by said crank-case, at opposite sides thereof, said members having their axes substantially aligned with that of the crank-case, and

being exteriorly stream-lined to progressively reduce their diameter toward their ends remote from the crank-case.

8. An internal combustion engine comprising a crank-case, a head fitted into one end of the crank-case to form a wall of the crank-case, and comprising a bearing for the crank shaft, projecting from such wall, and a fuel tank attached to the opposite end of the crank-case, a wall isolating the fuel tank from the crank-case, being formed by one or the other thereof.

JOHN L. DOLL. CLIFFORD W. ROGERS. 

